1. Field of the Invention
The present invention concerns a method for coded data transmission in half-duplex operation between data terminal equipment of two data stations, whereby a code device of the one data station transmits a phase-in program to the code device of the other data station and the other code device transmits an acknowledgment. 2. Description of the Prior Art
When data and an end identification are transmitted in half-duplex opertion, subsequently a change of direction can occur in order to be able to transmit data in the opposite direction. Changes of direction of this sort are introduced with change of direction programs which consist of one phase identification each, one first send identification each and one second send identification each. These change of direction programs are acknowledged from the opposing, remote station. Thereby, the crypto units are phased out in each case after the recognition of the end identification and are newly phased-in after the last bit of the first send identification. This method has the disadvantage that the efficiency of the data transmission is reduced by the change of direction programs to be transmitted with 120 bits each.
In order to raise the data transmission rate, it would be essentially conceivable to transmit the data in full-duplex operation. However, for this, a relatively large technical expense is required.